Table 4.

Effects of body composition on metabolism in deer mice ranging in age from 27 days to 1827 days

O2maxO2sum
BMRAge < breakpointAge > breakpointAge < breakpointAge > breakpoint
Body composition(N=54)(N=25)(N=30)(N=25)(N=30)
Heart massr=0.337, P=0.0145*r=0.642, P=0.00126*r=0.236, P=0.233r=0.443, P=0.0387r=0.333, P=0.0827
Lung massr=0.266, P=0.0565r=0.604, P=0.00287*r=0.358, P=0.0612r=0.420, P=0.0515r=0.392, P=0.0394
% fat contentr=0.298, P=0.0320r=0.601, P=0.00307*r=0.128, P=0.516r=0.439, P=0.0408r=0.424, P=0.0245
Hematocritr=0.280, P=0.0443r=0.413, P=0.056r=0.231, P=0.237r=0.462, P=0.0305r=0.347, P=0.0705
  • BMR, basal metabolic rate; O2max, maximal oxygen consumption in exercise; O2sum, maximal oxygen consumption in thermogenesis.

    Age breakpoints for O2max and O2sum (485 days and 483 days, respectively) were obtained from the complete data set (Table 2). Regressions were based on loge-transformed metabolic data and included the effects of loge-transformed lean tissue mass and age. Partial r and P values are shown; P values that remained significant after Bonferroni correction are indicated with asterisks (adjustedα =0.0167 for BMR and 0.0036 for O2max and O2sum).